Process for inspecting patterned wafers
US5355212A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 1993 |
| Grant date | Oct 11, 1994 |
| Priority date | — |
| Expiry date | Jul 19, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/95607
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of locating particle and defect features on a periodically patterned surface uses multiple threshold intensity levels to identify features in the data stream produced by scanning the surface with a light beam and detecting the light scattered from the surface. High thresholds are assigned to regions of the surface with high background scatter, while low thresholds are assigned to regions of the surface with low background scatter. The scattered light is detected with a wide dynamic range detector producing high resolution 12-bit pixel data capable of resolving the smallest particles and defects of interest in low scatter regions, while avoiding saturation in high scatter regions. Periodic pattern features are removed from the data by mapping features from a plurality of periodically repeating die on the surface to a single die map and looking for overlapping features. Unique, nonoverlapping features are determined to correspond to particles and defects. In one embodiment, only a portion of all the die on the surface are mapped at one time to reduce the possibility of accidental overlap of particle and defect features.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.